Molecular cloning and characterization of p56dok-2 defines a new family of RasGAP-binding proteins.
Chronic myelogenous leukemia (CML) is a disease characterized by the presence of p210(bcr-abl), a chimeric protein with tyrosine kinase activity. Substrates for p210(bcr-abl) are likely to be involved in the pathogenesis of CML. Here we describe the purification, cDNA cloning, and characterization of a 56-kDa tyrosine phosphorylated protein, p56(dok-2) (Dok-2), from p210(bcr-abl) expressing cells. The human dok-2 cDNA encodes a 412-amino acid protein with a predicted N-terminal pleckstrin homology domain as well as several other features of a signaling molecule, including 13 potential tyrosine phosphorylation sites, six PXXP motifs, and the ability to bind to p120(RasGAP). Dok-2 was shown to be 35% identical to p62(dok-1), a recently identified RasGAP binding protein from CML cells, and analysis of the expressed sequence tag data base revealed the presence of at least four additional proteins containing a Dok homology sequence motif. Dok mRNAs were primarily expressed in tissues of hematopoietic origin. These findings strongly suggest that a family of Dok-related proteins exists that bind to RasGAP and may mediate the effects of p210(bcr-abl) in CML.
Di Cristofano
A
A
Department of Human Genetics and Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
Carpino
N
N
Dunant
N
N
Friedland
G
G
Kobayashi
R
R
Strife
A
A
Wisniewski
D
D
Clarkson
B
B
Pandolfi
P P
PP
Resh
M D
MD
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins; D016044:Fusion Proteins, bcr-abl / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D006412:Hematopoietic Stem Cells / Q000737:chemistry; D006801:Humans; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000209:etiology / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D016601:RNA-Binding Proteins; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014018:Tissue Distribution
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C489560:DOK1 protein, human; C115089:DOK2 protein, human; C489561:Dok1 protein, mouse; C498444:Dok2 protein, mouse; C074561:GAP-associated protein p62; D020690:GTPase-Activating Proteins; D010750:Phosphoproteins; D011506:Proteins; D016601:RNA-Binding Proteins; D011505:Protein-Tyrosine Kinases; D016044:Fusion Proteins, bcr-abl